When removing a disc from an intervertebral space disposed between adjacent vertebrae, the conventional procedure is to fuse the adjacent vertebrae together. More recently, there have been developments in the field of disc replacement, namely disc arthroplasty, which involves the insertion of an artificial intervertebral disc implant into the intervertebral space. The artificial disc then allows limited universal movement of the adjacent vertebrae with respect to each other.
One such intervertebral implant includes an upper part that can communicate with an adjacent vertebrae, a lower part that can communicate with an adjacent vertebrae, and an insert located between these two parts. An example of this type of implant is disclosed in U.S. Pat. No. 5,314,477 (Marnay), the disclosure of which is hereby incorporated as if set forth in its entirety herein.
Instruments have been developed for preparing an intervertebral space for receiving an artificial disc implant. These instruments include a set of different sizes of trial implants, different ones of which are inserted into a cleaned out intervertebral space until the correct size trial implant has been determined, thereby determining the size of the actual disc implant to be permanently inserted.
In disc arthroplasty procedures, proper implant location assists in determining the kind of motion obtained from the device. Because proper implant positioning assists in patient recovery and spinal motion, fluoroscopy is used to visualize the position of the prosthesis and implant trial throughout the procedure.